They’re called methane hydrates and are sometimes known as “flammable ice.” If tapping methane hydrates ever becomes feasible, it once again would change the geopolitical map of the planet. Nations like Japan and India that lack their own conventional oil and gas resources suddenly could become energy power players.

The U.S. Department of Energy says “methane hydrates may exceed the energy content of all other fossil fuels combined” and “could ensure decades of affordable natural gas and cut America’s foreign oil dependence.”

But the possibility that fossil fuels could drive the world’s economies indefinitely — even the most conservative forecasts describe methane hydrates as a bounty greater than all other sources of natural gas combined — dismays many, who for decades have hoped scarcity eventually would wean the globe from its dependence on greenhouse-gas-producing technologies.

“Then you get into the question, are we going to stick with fossil fuels until we completely fry the atmosphere?” said Richard Charter, who is a senior fellow at the environmental group the Ocean Foundation and also a member of the Energy Department’s methane hydrates advisory committee.

The International Energy Agency said in a November report that the viability of methane hydrates as a fuel source will depend on technological advances as well as climate change policies. Meeting goals to reduce carbon emissions will require cutting back on all fossil fuels, even those derived from ice. There’s also the fact that methane is a potent greenhouse gas when released into the atmosphere, the IEA noted, and great care is needed in harvesting it.

There are huge challenges to producing natural gas from methane hydrates. But Japan hopes to come up with ways to develop the untapped resource within the next five to 10 years, and other nations are also pressing ahead on research, including the United States, which has vast amounts of the stuff beneath the permafrost of the Alaskan Arctic and deep in the Gulf of Mexico.

Methane hydrates are formed at crushingly high pressure and frozen temperatures, a condition found at the bottom of the otherwise warm Gulf of Mexico. The ice crystals caused problems for BP’s equipment as it tried to contain the 2010 Deepwater Horizon oil spill in the Gulf. Oil companies are well aware of their potential as an energy resource, but so far they’ve mostly been something to avoid while drilling.

National Energy Technology Laboratory Director Anthony Cugini said at this year’s Deloitte Energy Conference that whoever has his job in the coming decades could be talking about a hydrate energy revolution.

“These methane hydrates really create an opportunity that can move shale gas to the back page if you believe that. The resource is so large,” Cugini said.

But like during the decadeslong development of hydraulic fracturing — fracking — techniques that eventually led to the shale boom, there are many who question whether methane hydrates ever will become economical as a source of energy.

“The technical issues are not the biggest challenge right now. I think the biggest challenge is related to the economics of the situation,” said Carolyn Ruppel, who is working on the matter at the U.S. Geological Survey.

Among the challenges are the cost of transporting energy that comes from the Arctic and deepwater oceans, Ruppel said. It’s not like America’s shale gas, which is found all over the country.

America already has a glut of cheap natural gas from shale and no immediate need to develop methane hydrates. Other nations, however, have far different energy needs and are pushing harder to get methane hydrates developed.

The Japanese are paying so much to import natural gas that the cost of methane hydrates could make sense for them, said Tim Collette of the U.S. Geological Survey’s energy resources team. Some cost estimates for methane hydrates are 10 times higher or more than those of conventional natural gas. The Japanese hope to bring the cost of production down and make it more competitive with other energy sources.

Japan is also urgently looking for new energy as it moves away from nuclear following the Fukushima disaster, when three nuclear reactors melted down and radioactive material leaked out after an earthquake and tsunami in March 2011.

The energy consulting firm IHS Cera said it’s plausible to expect Japan to be using methane hydrates within 15 years.

South Korea could be next. Like Japan, it’s a developed and wealthy nation without its own oil and gas.

Asia could be the cradle of methane hydrates, as “necessity is often the mother of invention,” IHS analysts concluded in a recent report.

A pair of methane hydrate breakthroughs happened in the past year. Researchers on the North Slope of Alaska released natural gas from ice crystals within the permafrost by injecting them with nitrogen and carbon dioxide. The hydrate formation took in the carbon dioxide and released the methane, essentially exchanging molecules, while the research team lowered the pressure in the well to get the gas out.

Then Japan produced a flow from deepwater deposits off its shores through a depressurization technique. That involves drilling a well into a formation and pumping out the water. That causes the gas to break free as a result of the difference in pressure between the underground hydrate deposit and the well.

Charter, of the Ocean Foundation, said there are risks in developing methane hydrates. Those include blowouts and triggering of subsea landslides that release planet-warming methane into the atmosphere

“I would say right now they are at a similar development stage to that of the early Edison light bulbs, where half of them blew up,” he said